Voltage-controlled oscillators (VCO) are widely employed today in a multiplicity of electronic apparatus, particularly for modulating and de-modulating RF signals.
Such oscillators are mostly provided, in integrated circuit form, with RC multivibrators wherein the capacitor charge current is varied in response to a control pulse.
A typical example of a device of this kind is described, for example, in "Analysis and Design of Analog Integrated Circuits", pages 590-593, published by Wiley, 1977.
Devices of this kind require that the duty cycle of the synthesized waveform can be varied as desired without changing the oscillation frequency.
No suggestion from the prior art has been known which could meet said requirement.